An on-vehicle control system that controls sounds within a vehicle is disclosed, for example, in JP-7-159190A.
In a vehicle interior, various sounds such as music outputted from an audio device and voice guidance such as route guide outputted from a navigation device coexist. The music and voice guidance are not outputted in a coordinated or balanced manner with each other but are outputted independently of each other. Therefore, for example, if voice guidance from the navigation device is outputted when music from the audio device is being outputted in an extremely high volume, the outputted voice guidance will be buried in the music. The user may not be able to catch the voice guidance. Since these sounds are outputted regardless of user's physical condition, the user may feel that the sound level is not appropriate or miss the voice guidance when the user is in bad physical condition.